BADSVN2000

Hey people just a little question.

I drove my car further than up my street yesterday and had a boost guage set up finally. when I floored it in second it was quick, really quick like spun the back wheels when it came on full boost in 2nd gear on a 27 degrees C day! I looked down at the boost guage quickly and I am pretty sure it said 1.5bar.
The turbo's fitted were re-built 2000km's before I obtained them and were off a running car. My car has an ARC intercooler, apex'i power fc, apex'i filter pipes with HKS pods, I have a 3" Trust down pipe from the turbo's into a 3" 5Zigen rear exhaust, no cat!

I originally had the power fc in my old FD and that car had a really bad boosting problem (wouldnt go above 5psi on 1st turbo and 8psi on 2nd turbo) so I took it into the shop where it was built and they from memory just dialled more boost into the power fc but it made no difference, the isssue was also never resolved.

Could the power fc be making my car boost that high or will it be a combination of the power fc and the mods I have done to the car?

I took the car home straight after that high boost level reading (without boosting it) and parked it up. The car runs very smoothly still and starts every time, doesnt miss a beat etc, compressions are really good so I know the engine is still ok.
Engine is an import from japan which I think was re-built in japan soon before I owned it as it was/is very clean and it doesnt smoke, not even on start up.

paradoxbox

are you sure your boost gauge is accurate? it's most likely reading incorrectly, at 1.5bar your turbos would likely just fail then and there (or at least they will fail if you do it more than a few times).

GoodfellaFD3S

iTrader: (213)

What are you running for boost control? Sounds like you need to take your FD in to have your power fc sorted, immediately. You also might need to think about reinstalling a cat to give you some backpressure and thus more stable boost.

BADSVN2000

I think the boost guage is accurate? It is an Apex'i one, when idling it reads 400mmHg. I think this is read in Bar but if I am wrong I will feel like a right retard!!
I have normally only ever used Autometer gauges which read in PSI but this Apex'i one I got a good deal on so I got it.

And don't worry that was the first time i fully planted foot then drove it carefully home!

Here is a pic of my boost guage

theorie

iTrader: (31)

1.5 bar = 21.76 psi

22lbs on stock twins?!? highly unlikely. something must be wrong with your boost gauge.

BADSVN2000

Lets say there is a prob with my boost gauge and say it is running on 1bar, isnt that still about 14.3psi? if so then that is still high am I right?

I had a friend who was running his sock turbo's on 18psi but he had water injection and a few other bits and pieces to keep it together. I am not saying I want to run that amount of boost but just saying i could be possible couldnt it?

rexhvn

There is a member on the forum who has run as high as 22psi on his stock turbos still running strong... I beleive he is running 19psi at the moment...

Archie

iTrader: (-1)

I've been running 14psi on stock non-seq twins for quite awhile. I wouldn't recommend more than 15psi, depending on what your mods are and your tuning.

Some of my mods:
Streetport
M2 large intercooler
Pettit Intake
3" Mid/Downpipe
Greddy Catback

I would definately listen to Goodfella and get it sorted out! Stock twins IIRC are not even efficient past 18psi (somebody PLEASE correct me). At least get your PFC looked at. Good luck and I'll cross my fingers for your Hitachis

Archie

iTrader: (-1)

You know, I think I remember reading that. I'm probably just being too conservative with 14psi.

rexhvn

I'm pretty sure 15psi is maxing the stock turbos, anything more is increasing the heat more than power... but 14psi is just right in my opinion! Once I get a front mount and ECU, i'll set it to 14psi...

DaleClark

iTrader: (55)

Most likely you have a simple boost controller problem. If one of the vacuum lines to the wastegate actuators has come off, the wastegate will stay closed and boost will go through the stratosphere. I think you'd really have to work a boost controller to get boost to go THAT high.

I doubt something's wrong with the gauge - Apexi makes good gauges, and as long as it reads zero when the engine is off it's most likely on the money. Bad plumbing to the gauge would mean a boost leak, so it would show you a lower number.

Of course, the real problem is when you get the car fixed and boosting properly it will always seem slow .

Dale

GoodfellaFD3S

iTrader: (213)

I agree with Dale.

Like I asked way back in post #3, what are you running for boost control?

paradoxbox

Not to disagree with anyone but my car came from Japan with an old Apexi EL gauge and it was wrong (Mind you it did read above zero with the engine off) but I have also had other cars from Japan where the boost gauge read zero with the engine off but on boost the dial goes over 2 bar (which was clearly wrong, the actual boost being reached was about .9bar!).

I would recommend just grabbing a new gauge, you can get a cheapo boost gauge for around 12$ at most auto stores (It's meant for testing not as a permanent fixture) and then you will be able to see what your real boost is.

Something in old mechanical boost gauges tends to fail and they start reading strangely both high and low. 400mm HG is kind of low vacuum at idle unless you have a port job, but I am willing to bet your gauge is just wrong or you have a vacuum hose leak somewhere.

rash_rvg

iTrader: (1)

besides the obvious boost control problem other members have pointed out, WHY the hell are you reading the bost from a gauge you can't even be sure of what it was reading and from the PowerFC? Or you don't have a Commander?

2FAST7S

you stated you looked down at the gauge...maybe it was the angle? Quick glance at a funny angle.
Even if this is the case, it seems way too much boost...

Who installed the turbos? oversight maybe.

I had the c clip that holds the sec. w/g actuator arm break/fall off (sec. turbo)....check that.

Matt Hey

Although Apexi boost gauges are usually high quality, I too doubt you hit 1.5 kg/cm^2 = 1.47 bar = 21.34 psi. The PowerFC will fuel cut if boost goes .25 kg/cm^2 = 3.56 psi above what the boost is set for in the PowerFC. Most maps I've seen are set for sane boost levels like .7 or .8 kg/cm^2. Many stock turbo setups would not boost that high but it is possible without the cat. You should probably have your wastegate ported or the PowerFC may be unable to control boost without the cat. The 7 will feel really fast in cold weather with half the boost your gauge shows. Your motor is probably fine and it should be safe to drive it around if you stay out of boost. You do want to figure out what's going on before boosting. Another boost gauge (or FC Commander boost reading) is a good start as suggested.

BADSVN2000

Thanks for all of your input, I do appreciate it.

Hand conroller:
To answer your question, I am used to the psi readings on boost guages and when I got this gauge I thought it was in psi and a freind who was following me at the time of the reading told me it was 1.5bar not 15psi like I thought it was, so please do not think I am retarded as I do not know everything.

Power fc:
I dont have a hand controller but will be getting one as soon as I can afford it. The reason I fear that it may be boosting so high is when I took it back to the garage that built the engine in my old FD that was having boost problems, they just plugged in a laptop and told the pfc to give the engine more boost but I cannot remember how much they told it to give or even if they put the boost back to what it was originally (it was 2 years or so ago and shortly after the garage owner took off and disappeared).
I will be taking it to RX7 Heaven as soon as I can to have it tuned on the dyno and pfc sorted out.

The gauge reads 0 when engine is off.

Thanks again

BADSVN2000

Hey all I just thought I would give you an update on the problems I was having with the boost.
I was PM'd by user kerry chandler and he offered to help with the problem using datalogit. I have just returned from his house with new boost settings. We found that the boost had been set to 1bar on the pfc and with my mods it was spiking to 1.5bar. We reduced the boost to 0.85bar and it is now bootsing at 1bar solid and is running very well. I have a good fuel map that was previously loaded on but may still take it to get tuned at RX7 Heaven.

Thanks for all your help I am grateful that once again this forum has been of great assistance.

Cheers,
Jon